Revs drop when thermo's come on + crap idle help

[TheInterceptor]

Hello all! Here's a double header problem thread which may or may not be related to each other, so here it goes, both in one, sorry in advance for the long post!

So the story goes like so. When hot (of course) and idling in bumper to bumper traffic, the thermos will come on when they do and while doing so, it makes the car shudder, dropping the revs down to roughly 400rpm.

Previously in the past 9000 or so kms, i have cleaned the ISC, throttle body (while still on motor), checked for vac leaks with WD (produced no results), fitted new air filter, new thermostat, fitted new idler pulley, new plugs, new fuel filter, and a new fuel pump.
I did reset the ECU a few months ago when i bought the car using the instructions posted on this board. (unsure when the drops started, i have a great memory )

Havent needed to use AC much as yet but im sure that makes it drop a touch when engaged. Nothing else causes a drop.

I cant really think of anything i can pinpoint that of which would cause this to happen? Any ideas??

The car doesnt start perfectly every time either and the idle isn't perfect. Replacement of the idler pulley made it feel better, putting in BP 98 makes it start better and idler a LIL better, i suspect the servo i always went to has crap fuel as it pinged once apon starting and once every few times i punch the go pedal from idle.
I also noticed at idle the tensioner moves about with the rough idle, relevent?? I know its not supposed to budge! It feels like it misses every few revolutions. Its done this for a good while now. Car has 141xxxkms on it.

Any ideas? Think i might do a major service next and replace a whole bunch of things.
Cheers!

[Maka]

Hi Theinterceptor, have a look at this- www.fordforums.com.au/showthread.php?t=11362956

Do a good service on the engine, replace fuel filter- any water in the fuel will cause havoc, the fuel rail is not made of stainless steel & rust deposits inside the fuel rail will form soon (if not already) & start blocking fuel reg & injectors. For some mechanics its a throw away item & replace with new at service time. Did you lube the iac plunger shaft after cleaning? The both problems may be associated yes so check your battery & alternator output also. Good luck with it & keep us informed

cheers,Maka

[cobramania]

Sounds like Battery &/or alternator problems to me. Obviously don't do this in traffic, but try with the headlights on high beam. Do they dip in brightness any/significantly when the thermos cut in? Does the revs/idle drop even further than usual with the headlights on, or does the car stall? Try it with the fan on high too, but A/C off, then with A/C on & see what difference it makes.

Even on a cool day, sitting at idle, turn all electrical accessories on you can, fan, radio, headlights, cabin lights, put some reasonable load plugged into the ciggie lighter if possible (air pump, etc.), does this have the same affect on the revs, idle speed as the thermos cutting in does?

[TheInterceptor]

Originally Posted by Maka

Hi Theinterceptor, have a look at this- www.fordforums.com.au/showthread.php?t=11362956

Do a good service on the engine, replace fuel filter- any water in the fuel will cause havoc, the fuel rail is not made of stainless steel & rust deposits inside the fuel rail will form soon (if not already) & start blocking fuel reg & injectors. For some mechanics its a throw away item & replace with new at service time. Did you lube the iac plunger shaft after cleaning? The both problems may be associated yes so check your battery & alternator output also. Good luck with it & keep us informed

cheers,Maka

Hey Maka! That link sounds exactly like my problem. Im unsure how old my battery is and when i bought the car the alternator was covered in black grime ..so who knows how good it is. Seems to be behaving so far. Ive owned this car since May this year so its still unknown.

Did a service on it 1500kms ago, new oil, oil filter and air filter. But ive been filling up with the same fuel ever since i bought the car, but on long trips, other fuels (from Shell/Caltex) didnt make a difference. So maybe the potential shoddy fuel was the final straw?
I didn't lube the IAC plunger, i drowned it in WD though so it should be right.

Originally Posted by cobramania

Sounds like Battery &/or alternator problems to me. Obviously don't do this in traffic, but try with the headlights on high beam. Do they dip in brightness any/significantly when the thermos cut in? Does the revs/idle drop even further than usual with the headlights on, or does the car stall? Try it with the fan on high too, but A/C off, then with A/C on & see what difference it makes.

Even on a cool day, sitting at idle, turn all electrical accessories on you can, fan, radio, headlights, cabin lights, put some reasonable load plugged into the ciggie lighter if possible (air pump, etc.), does this have the same affect on the revs, idle speed as the thermos cutting in does?

Hey there! So what i have done is ive cleaned the battery terminals and then tried this out. (By the way im unsure if i had the battery disconnected enough to reset the ecu)

I started the car then selected D, then loaded the heck out of the electrics. So radio on, lights on high beam, fan on max plus air con on (which turned the AC thermofan on), demister, foot on brake. I have a cig lighter volt meter which read 13.9 unloaded then dropped to 12.5 when loaded with the above. Then i selected reverse to turn the reverse lights on which dropped the volts to 12.1!

Volts read 14.0 unloaded in N.
Read 13.2 loaded in N.

Does this sound fine?

Turning all loads on drops the revs down to 400rpm like when the thermo's cut in in traffic. The headlights dont dim under any circumstance. It has never stalled!

Thanks for the replys gents!